Brake boosters and brake units are already known from the related art. Unexamined patent application DE 10 2012 014 361 A1, for example, describes a brake booster for a main brake cylinder of a motor vehicle, which includes a drive motor and a gear unit connecting the drive motor to a pressure piston of the main brake cylinder. In this case, the gear unit includes a section which is designed as a spindle gear unit in order to convert a rotary motion of the drive motor into a translational motion of the pressure piston for actuating the main brake cylinder. For this purpose, the spindle gear unit includes a spindle nut including a female thread and a spindle rod including a male thread, the two threads engaging into each other in order to convert a rotary motion into a translational motion.